The present invention relates to a closure for a canning glass container with a glass cover. More particularly it relates to a closure for a canning glass container with a glass cover and also with a rubber ring which extends over an opening rim of the container, projects outwardly, is located between the canning glass container and the glass cover, and is removable in a radial direction by hand. Only during canning a clamp is provided which abuts against a lower side of the flange of the canning glass container and the upper side of the glass cover, and the cover is pressed with interposition of the rubber ring against the upper circular rim of the canning glass container.
Canning glass containers of the above mentioned general type are known in the art. Some of such containers is disclosed, for example in the U.S. Pat. No. 3,991,897. The upper rim of the container disclosed in this reference has a cross-section which is rounded so as to form a semi-circular surface. The glass cover has a supporting rim. The upper rim of the container engages deeply into the rubber ring to suppress great forces. Since the glass cover after its manufacture is somewhat distorted after cooling and each glass cover is not tested, with this solution the supporting rim of the glass cover must be grinded.
Another canning glass container in the U.S. Pat. No. 3,519,159. Here, the upper circular rim is provided with a circular raised part which extends in a cross-section over an angular region of approximately 180.degree.. A cover of this container is formed as a screw cover and composed of metal. A ring seal arranged between the upper rim of the container and the screw cover has a great thickness so that the upper rim of the container can deeply engage into the seal. This requires high forces which can be provided only by a screw cover. This construction is therefore not suitable for a canning glass container with a glass cover and with a rubber ring removable by hand.